Sandbox Reserved 110: Difference between revisions

MraY is a membrane-bound enzyme, for which the N and the C termini are located on the periplasmic side. This protein is made of four extracellular loops, five cytoplasmic loops (named A,B … and E) and ten transmembrane helices named TM1 to TM10. Though, TM9 is cleaved by a glycin residue into two helical segments named TM9a and TM9b. Furthermore, there is an additional helix between TM9b and TM10, which is only 11 residues long and is called TM9c. This helix contains a HHH motif (H290, 291 and 292) which plays a role in the enzyme’s substrat selectivity and is a part of the catalytic site <ref name="one">PMID:29778697</ref>. For example; they interact with tunicamycin and MD2. This small loop binds two Ni2+ ions, one on the two first histidines and the other one on the last one. Another part of this site is the residues corresponding to Asp117 and Asp118  which are involved in Mg2+coordination <ref name="four">PMID:29438582</ref>.TM5–TM10 and loops C and D also play a role in the catalytic site and contain many polar and charged amino acids residues <ref name="one">PMID:29778697</ref>.  Also, some polar and charged amino acids on TM9b and loop E are pointing toward the active site, making it even more hydrophilic <ref name="four">PMID:29438582</ref>.